See also Ex.

6, second Phrase.
MELODY .-- Any succession of _single_ tones is a melody.

If we strike the keys of the piano with two or more fingers of each hand simultaneously, we produce a body of tones, which--if they are so chosen that they blend harmoniously--is called a Chord; and a series of such chords is an illustration of what is known as Harmony.

If, however, we play with one finger only, we produce a melody.

The human voice, the flute, horn,--all instruments capable of emitting but one tone at a time,--produce melody.
Melody constitutes, then, a _line of tones_.